#include <stdio.h>
#include <malloc.h>
#include <stdbool.h>
typedef struct TreeNode
{
    TreeNode* left;
    TreeNode* right;
    char val;
}TreeNode;
bool _isSymmetric(struct TreeNode* left, struct TreeNode* right)
{
    if (left == NULL && right == NULL)
        return true;
    if (left == NULL || right == NULL)
        return false;
    return left->val == right->val
        && _isSymmetric(left->left, right->right)
        && _isSymmetric(left->right, right->left);
}

bool isSymmetric(struct TreeNode* root) {
    if (root == NULL)
        return true;
    return _isSymmetric(root->left, root->right);
}

int main()
{
   
    return 0;
}
